Across the period of adolescence, academic achievement becomes an increasingly important determinant of social, academic, and economic opportunities. Yet, little is known about the factors that affect achievement in specific academic learning situations as well as whether and how the interrelationships among the factors change from early adolescensce to college years. The proposed research focuses on an important, but neglected aspect of academic achievement: the character, determinants, and effectiveness of students' study behavior. The central hypothesis of the study is that as age increases over the period of adolescence, academic achievement is increasingly determined by students' study activities. More specifically, it is hypothesized that this age trend stems from (a) the increased importance of study activities due to corresponding increases in both the cognitive transformational requirements (number of organizational, integrational demands placed on students) and volitional latitude (degree of opportunity for student-initiated effort) of courses; and (b) increased individual differences in certain cognitive and affective characteristics that affect study behavior (e.g., knowledge of study procedures, capability of analyzing study demands; locus of control, expectancy of success). A model that displays the interrelationships among study activities, achievement, and the two dimensions of both student and context factors is presented as a framework for the proposed research. A three-year two-phase investigation is proposed. First, a preliminary assessment of the merit of the hypotheses will be conducted involving students drawn from three strata: junior high, high school, and college; a battery of cognitive, affective, and study behavior instruments; and primarily descriptive methods of analysis. Second, the hypotheses will be refined and subjected to experimental verification involving the manipulation of task conditions relative to the two context dimensions of interest.